Profile stitching machines

ABSTRACT

A profile stitching apparatus has a power driven sewing machine and a tracker plate having a slotted profile arranged to be moved with the slot in register with the needle of the machine to sew along the profile. A transmission couples the plate to the drive of the machine to allow the plate to move relatively to the machine. The transmission includes two pairs of contra-rotatable pinions each cooperable with a rack and each operable to cause movement of plate in different directions. The transmission also includes structure which ensures that the tracker plate is moved only when the needle is clear of the plate.

llnlted States Patent 1191 Palmer PROFILE STITCHING MACHINES [75] Inventor: George William Palmer, Sudbury,

England [73] Assignee: Stateside Machinery Co. Ltd.,

London, England [22] Filed: Oct. 23, 1973 [21] Appl. No.: 408,998

[52] US. Cl. ..ll2/121.l2

51 Int. Cl DOSb 21/00 [58] Field 0fSearch.....l12/12l.l5,121.l2,121.11, 112/102, 118,90, 86

FOREIGN PATENTS OR APPLICATIONS 1,455,129 9/1966 France 1l2/l2l.l5 1,048,807 ll/l966 United Kingdom 112/12115 Primary !i.\'aminerWerner H. Schroeder Attorney, Agent, or Firm-Edwin E. Greigg [57] ABSTRACT A profile stitching apparatus has a power driven sewing machine and a tracker plate having a slotted profile arranged to be moved with the slot in register with the needle of the machine to sew along the profile. A transmission couples the plate to the drive of the machine to allow the plate to move relatively to the machine. The transmission includes two pairs of contrarotatable pinions each cooperable with a rack and each operable to cause movement of plate in different directions. The transmission also includes structure which ensures that the tracker plate is moved only when the needle is clear of the plate.

17 Claims, 9 Drawing Figures PATENTEU HAR 2 5 I375 PROFILE STITCHING MACHINES BACKGROUND OF THE INVENTION This invention relates to profile stitching machines.

In the manufacture of, for example, the collars and cuffs of shirts and similar garments, it is necessary to join together by stitching, at least two layers of materials and in order to obtain a satisfactory article, the line of stitching should follow anaccurate path and not diverge to any great extent from this path.

To achieve such accuracy, stitching templates or tracker plates are used comprising upper andlower planar members between which layers of materials to be stitched can be located, a slot having a profile corresponding to the required line of stitching being provided in each planar member and the slots being aligned when the planar members are arranged in superposed relationship to accommodate the needle of a sewing machine allowing the needle to follow the profile of the slots.

OBJECTS AND SUMMARY OF THE INVENTION It is an object of the present invention to provide profile stitching apparatus wherein a template or tracker plate is moved by operation of a sewing machine to allow the needle to stitch along the profile of the template or tracker plate.

A further object of the invention is to provide profile stitching apparatus wherein a template or tracker plate is moved in response to operation of the sewing machine to allow the needle of the machine to follow the profile of the plate, but only when the needle is in the raised position out of contact with the workpiece.

According to the present invention there is provided profile stitching apparatus including a power driven sewing machine, a stitching tracker plate having a slotted profile arranged to be moved with the slot in register with the needle of the machine to sew along the profile, transmission means arranged to couple the plate to the drive means for the machine to allow the plate to move relatively to the needle of the machine, said transmission means including a gear assembly having a first pair of contra-rotatable pinions co-operable with a rack operatively connected to a first carriage member and arranged to engage guide means arranged along one longitudinal edge of the tracker plate to permit the tracker plate to be moved in a direction transversely of the one longitudinal edge, and the gear assembly including a second pair of contra-rotating pinions cooperable with a second rack operatively connected to a second carriage member arranged to engage further guide means arranged along another lateral edge of the tracker plate to permit the tracker plate to be moved in a direction different from the first mentioned direction, and means included in the transmission means for moving the tracker plate in timed relationship with the operation of the machine such that the tracker plate is moved only when the needle is clear of the workpiece.

The tracker plate may have first guide means extending along one longitudinal edge of the plate and second guide means extending along one lateral edge of the plate and said first and second guide means being arranged to co-operate with control means associated with the transmission means of the machine to control the relative movement between the tracker plate and the needle of the machine.

LII

, tion of the plate in discrete steps to give an intermittent In a preferred embodiment of." the invention the tracker plate guide means comprise upstanding rails extending along one longitudinaledge and one lateral edge of the plate and cooperable with a pair of carriage members having microswitches associated therewith, the tracker plate being moved by the transmission means past the needle and the movement thereof being. controlled in response to the actuation of the microswitches.

The pinions are arranged to rotate selectively in response to energisation of a respective one of'a plurality of clutches; energisation of any one of the clutches causing the respective one of the output pinions to rotate to move the rack associated with the pinion.

The transmission means includes intermittent drive means which is arranged to impart intermittent movement to the template or tracker plate to move the plate in timed relationship with the operation of the machine thereby ensuring that the template is moved only when the needle is raised clear of the workpiece. Such intermittent drive means includes a modified Geneva gear mechanism having four pins located on a plate integral with an input shaft and arranged to successively engage six slots in a star plate of a Geneva gear; the rotation of the input shaft bringing the pins sucessively into engagement with the slots in the star plate to effect rotamovement thereof. This intermittent motion is transmitted to the gear assembly direction mechanism to control the movement of the tracker plate.

The invention will now be described by way of example only with particular reference to the accompanying drawings wherein:

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view of part of the profile stitching machine of the present invention;

FIG. 2 is a plan view of the carriage drive mechanism and the Geneva gear mechanism for intermittent movement of the tracker plate;

FIG. 3 is a section of the carriage drive mechanism taken along the line 3-3 of FIG. 2;

FIG. 4 is a section of the Geneva gear taken along the line 4-4 of FIG. 2; 1

FIG. 5 is a section taken on the line s s of FIG. 1

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, the sewing machine 1 has a machine head 2 of conventional type containing the mechanism for effecting reciprocatory movement of the needle 3 (FIG. 5) to perform a sewing function in conjunction with a thread carried by a shuttle arrangement located beneath the working surface of the machine. The needle 3 is driven from an electric motor 4 (FIGS. 1 and .7) coupled to the needle driving mechanism (not shown) through a main transmission which includes a clutch/brake unit 5 through which power from the electric motor 4 is transmitted to the machine 1. A template drive mechanism which imparts movement to a stitching template 6 located on the working surface of the machine, is connected to the main transmission shaft 1 coupled through drive means 8 to the output shaft of the clutch/brake unit 5.

The template transmission includes an intermittent drive mechanism 9 (FIGS. 1, 2 and 4) which is arranged to impart intermittent movement to the template 6 to synchronise the movement of the template-6 with the movement of the needle 3 so that the template is moved only when the needle is clear of the material being stitched.

The intermittent drive means 9 comprises aIGeneva type mechanism (FIG. 4) having an input shaft 13 driven by a take off drive means 10 from the main transmission shaft 7. Four pins 11 are located on a plate 12 formed integrally with the shaft 13 and equidistantly spaced around the periphery with their polar axes parallel to the axis of the shaft 13. As the shaft 13 is rotated, each of the pins 11 engages in turn with one of six slots 14 in a star plate 15 of the Geneva mechanism which is mounted for rotation about an axis 16 parallel to, but spaced from the axis of rotation of the input shaft 13. The arrangement operates in the usual manner of a Geneva mechanism in that as the input shaft 13 is rotated, the pins 11 are brought successively into engagement with the slots 14 in the star plate 15 to ro-, tate the star plate in steps to thereby give an intermittent output.

The star plate 15 is connected to the input shaft of a direction gear box 17 by means of shaft 18 and universal couplings 19, 20; the gear box 17 controlling the direction of movement of template 6 so that the template is also moved intermittently.

A disc 21 which serves as a light shield is mounted on the input shaft 13 of the Geneva mechanism for rotation therewith, the disc 21 having two orifices 22, 23, arranged at diametrically opposite points of the disc 221. A light source 24 mounted on the machine body is positioned on one side of the disc 21, the light from the source being'arranged to pass through one of the orifices e.g. 22 as shown in H6. 1, to irradiate a light sensitive device 25, located on the other side of the disc 21 remote from the source 24. The light sensitive device 25, when irradiated, produces a signal which overrides the control of the main motor 4 and the clutch/- brake unit 5; the orifices 22, 23, being arranged such that the light sensitive device 25, is operated to ensure that when the clutch is disengaged, the transmission is brought to a standstill with the needle 3 in the raised position clear of the tracker plate 6.

The direction gear box 17 (FIG. 2 has a first pair of contra-rotating output shafts 26, 27, the axes of which lie in a first plane, and a second pair of contrarotating output shafts 28, 29, the axes of which are in the same plane as and normal to the axes of the first pair of shafts 26, 27. The shaft 18 is universally coupled to the input shaft of the direction gear box via coumeshes with pinion 33 ofa reduction gear train. Pinion 33 is mounted on shaft 34 which has a further pinion 35 thereon arranged to mesh with pinion 36 mounted on an output shaft 37 which is parallel to and spaced from shaft 34; the pinion 36 rotating in the opposite direction from that of pinion 35.

The second pair of output shafts 28, 29 are driven through bevel gears 38, 39 on shafts 34, 40 respectively and meshing pinions 41, 42 in a similar manner to the first pair of output shafts 26, 27. Each output shaft 26, 27; 28, 29; has associated therewith a respective output pinion 43, 44; 45, 46; which is arranged to be operatively coupled to the respective output shaft 26, 27; 28, 29; to effect rotation thereof in response to the energisation of the winding of a respective electromagnetically operable clutch 47, 48; 49, 50. Each pair of output pinions are permanently meshed with a respective rack 51, 52, and the racks lie normal to one another in a horizontal position below the working surface of th sewing machine as shown in FIG. 1.

Since the output pinion 43, 44 are both permanently meshed with the rack 51, it follows that the clutch 47, 48 of one only of each pair of output shafts 26, 27; 28, 29; may be energised at any one time so that only one output pinion e.g. 43, 45, of each pair may be driven by the main transmission at. such time. When one pinion e.g. 43, is being driven, the other pinion 44 of the pair is rotated in the same sense through the rack 51 and thus rotates freely on its output shaft 27.

Thus, by selective energisation of the clutches 47, 48; 49, the racks 51, 52, may be each moved to and fro along a path aligned with respective longitudinal axes of the racks.

Each rack 51, 52, is connected through a linkage 53, 54 respectively to a carriage 55,56, mounted above the work surface, the carriages 55, 56, each being adapted to engage with an associated guide rail 57, 58 respectively on the template 6 (see also FIGS. 8 and 9). The work surface has therein a pair of slots 59, 60 one normal to the other through which the linkages 53, 54, project. Thus movement of the racks 51, 52, caused by rotation of the output pinions 26, 27; 28, 29; is transmitted through the respective linkages to the carriages 55,56 and the template 6 located on top of the working surface.

The carriages 55, 56 comprise a control carriage 56 for moving the template 6 in a first path and a side carriage for moving the template 6 in a path normalto the first path. Each carriage comprises a main body 61, 62 carrying at least one pair of guide wheels 63, 64; 65, 66 mounted with their axes of rotation vertical, the wheels of any pair being adapted to engage one on each side of a respective guide rail 57, 58 of the template 6 so that the carriage 55, 56 may move freely along the length of the guide rail 57, 58 but when moved horizontallynormal to the length of the guide rail will, by virtue of engagement of the wheels 63, 64; 65, 6'6 with the guide rails move the guide rails and hence the template 6.

Microswitches M/Sl, M/S2 (FIG 7) mounted on the carriages have the contacts in engagement with the guide rails 57, 58 on the template 6, the contacts of the microswitches being held by the respective rail against the bias to the open position when so engaged, when the carriages are in engagement with their respective guide rails.

The main body 62 of the control carriage 56 is pivotable between a raised and lowered position. A reset microswitch M/S3 mounted on the carriage 56 is operated by the pivotal movement of the main body 62, for a purpose hereinafter defined.

The template 6 comprises a pair of rectangular plates 67, 68 connected one to the other through a hinge 69 adjacent one longitudinal edge. Thus,.the plates 67, 68 are pivotable to an open position to enable the layers of material 69 (FIG. 5) to be stitched together to be placed therebetween, the plates 67, 68 being pivotable to a closed position to locate the material to maintain it in the correct position within the template 6. Each of the plates 67, 68 has a slot or track 70, 71 defining the path and profile required for the stitching of the material, the slots 70, 71 being aligned when the template 6 is in the closed position. The slot 71 in the lower plate 68 is adapted to engage with a guide device which comprises a raised tubular element 73 projecting from the working surface of the sewing machine 1 and arranged concentrically with the needle 3 to thereby locate the template 6, and hence the path and profile to be stitched, relative to the needle. The cotton (not shown) from the shuttle (not shown) mounted beneath the working surface passes up through the bore of the guide device 73, which is rotatable in bearing member Guide members 75, 76 extend outwardly from two adjacent sides of the template 6 to lie in the same plane as the lower plate, the guide members extending over the length of the respective sides. The guide rails57, 58 extend along the length of the outer edge of each of the guide members, and extend upwardly normal to the plane of the guide members 75, 76. Thus, the guide rails 57, 58 are normal one to the other. The longer guide rail 58 is'adapted to be engaged by the control carriage. 56 and the shorter guide rail 57 by the side carriage 55.

The guide rails 58, 57 each have a number of notches 77, 78 formed along the upper edges thereof notches allowing the contacts of the microswitches M/Sl, M/S2 mounted on the carriages to be actuated. Thus, when a microswitch e.g. M/Sl is aligned with a notch e.g. 77 the contacts of the microswitch which are normally open are closed since the contacts are no longer held open against the bias by the guide rail 58.

The operation of the sewing machine is controlled through an electrical control circuit (FIG. 7). Current for the control circuit is obtained via line 80 from the mains supply which is supplied to a transformer 81 arranged to give a 24 volt output. The output of the transformer is fed to a rectifier 82 to provide a low voltage DC output on line 83. The DC output is passed through a capacitance smoothing circuit (not shown) toprovide a steady 24 volt DC for the control circuit.

The microswitches M/Sl, M/S2 on the carriages 55, 56, are connected in series so that before the electrical circuit can be completed the contacts of both the microswitches M/Al,M/S2 must be closed and thus, the control circuit is not completed until both carriages 55, 56 are in predetermined positions relative to the template guide rails 57, 58.

When the contacts of both the microswitches M/Sl, M/S2 are closed, the DC. level on line 83 changes and pulses are produced by a pulse generator of a sequential unit 84 which also. includes a decade counter. The two microswitches M/Sl, M/S2 are arranged as an AND gate and the pulses are applied direct to the decade counter, the output signal of which is then transferred to a binary coded decimal decoder which in turn feeds ten transistor amplifiers to give a ringcount ofl0. The decade counter and decoder are preferably both monolithic integrated circuits of the transistor/transistor logic type. A reset line R is connected to a built-in feature of the counter and a pulse transmitted therealong overrides all stored information in the sequential unit 84 and resets the counter instantly to stage 1. The reset line R is connected directly to the reset microswitch M/S3 on the control carriage 56. Output signals from the sequential unit 84 are supplied via programme selector unit 85 to a direction control unit 85a and also to module D which includes a thyristor D1 which is fired when the thyristor trigger receives an output signal from the sequential unit 84 in a selector unit 85 when the counter thereof is reset to stage 1. The firing of the thyristor Dl causes an output signal to be sent before the contacts of M/S4 move to the position shown via line 86 to effect energisation of a drop solenoid 87 associated with control carriages 56, thereby allowing a spring latch to be released by actuation of the armature to cause the control carriage 56 to pivot downwardly into engagement with the tracker plate 6. When the control carriage 56 is lowered, contacts of a double pole microswitch M/S4 are actuated to move into the position shown and remove current from the winding of the drop solenoidto prevent overheating thereof and cutting off the thyristor D1 of module D and making power available to the electromagnetic clutches 47, 48; 49, 50; of the directional gear box 17 as will be described hereinafter.

The output signal derived from the last step of the sequential unit 84 is arranged to supply a finish signal to the module D via programme selector unit 85 to trigger a second thyristor D2 which then provides an output signal for energisation of the winding of a lift solenoid 88 on the control carriage 56 to cause the main body of the control carriage 56 to be lifted from engagement with the template 6. Lifting of the carriage 56 causes actuation of the contacts of a double pole microswitch M/SS previously in the condition shown in FIG. 7 to supply a stop signal to the clutch/brake unit 5 to disconnect the driving clutch and apply the brake to stop the machine. When the main body of the control carriage 56 is lifted to theraised position by energisation of the'solenoid 88, the contacts of the microswitch M/S4 are actuated to cut off power to microswitches M/Sl, M/S2 and to the solenoid 188 to prevent overheating thereof. A spring latch which engages automatically when the carriage is lifted, maintains the carriage in the raised position.

The programme unit 85 is a plug-in module on the control panel of the machine and includes a diode matrix which receives pulses from the sequential unit 84 and is connected to the direction control unit 85a The latter unit includes four power transistors connected in circuit with a capacitor/resistor network to give a predetermined time delay in accordance with the time constant of the circuit when each transistor is triggered. Each transistor controls a respective one of the electromagnetically operable clutches 47, 48; 49, 50; in the direction gear box 17. Thus the outputs from the sequential unit 84 are arranged to render conductive selected diodes of the matrix. The particular diode or diodes rendered conductive is/are determined by the wiring of the matrix and this is determined by the sequential movements required for the template to follow the profile of the slot on the particular template used. Thus, an output signal originating from the sequential unit 84 is directed to the appropriate power transistor of the direction control unit 85a via the programme unit matrix. The R/C time delay at the time of stitching enables the machine to form two or more stitches in the corners of the work being sewn.

The programme selector unit 85 is designed as a plug-in unit and thus when a different template is used having a differently profiled slot, an appropriate programme selector unit 85 must be plugged into the machine as shown in FIG. 1.

In certain circumstances, not all the steps of the sequential unit 84 are required to perform a particular operation and a programme advance switch 89 is mounted on the control carriage 56; operation of which sends a pulse to the sequential unit 84 to step the sequential unit round one step. The programme advance switch 89 operates a pulse generator the required number of times to step the unit round to its starting position i.e. stage 1 and a feed back signal holds the sequential unit until microswitch M/S4 is activated upon the dropping of the carriage. Indicating lamps I are provided on a control panel on the sewing machine to indicate which step of the sequentialunit is in circuit.

Thus, when the counter of the sequential unit 84 is stopped a signal is not only sent to the programme unit 85, but also an indicator lamp is illuminated on the control panel I to provide a digital read out at 90. The read out provides an indication of the stage at which the machine is.

All of the units of the circuit are arranged to be plugin units so that if a fault occurs in a particular unit it may be replaced by spare units to enable the machine to continue in use while the faulty unit is being repaired.

The operation of the above described embodiment is as follows:

The guide member 73 of the needle plate engages in the slots in the tracker plate 6. In the off position of the sewing machine, the control carriage 56 is held in the raised position by means of an arm (not shown).

.The material 69' to be stitched is located between the plates 67, 68 of the template 6 and the template is placed under the control carriage 56 with the slots located over the guide member 73. When the template 6. is in the correctposition for the commencement of a machining cycle, the contacts of the reset microswitch M/S3 are closed. A circuit is completed to the sequential unit 84 (before the contacts of switch M/S4 move to the position shown) to cause the counter to be reset to the first counting position. The sequential unit in this position sends an output signal to thyristor D] of module D which controls the supply of power to the drop solenoid 87.

When the winding of the drop solenoid 87 is energised, the armature thereof is moved against a spring bias causing the spring latch which holds the control carriage in the raised position, to be moved into alignment with a recess in the control carriage to allow the control carriage 56 to drop to the operative position. When the control carriage 56 is lowered, the contacts of the microswitch M/S4 are actuated to remove current from the winding of the drop solenoid 87 to prevent overheating thereof as previously described.

The actuation of switch M/S4 also cuts off the thyristor D1 of module D and makes power available to all the electro-magnetic clutches 47, 48; 49, 50; of the directional gear box 17.

The microswitches M/Sl, M/S2 on the carriages 56, 55 respectively are connected in series and when the contact of both switches are closed on alignment with the V-shaped notches in the guide rails of the template, a signal pulse is supplied to the sequential unit 84 to advance the counter thereof by one step. The stepping of the counter by one step causes a pulse to pass through the diode matrix of the programme'unit 85 to the direction control unit 85a, which provides a current path to a preselected one or two ofthe windings of the clutches 47, 48; 49, 50; of the direction gear box 17. Thus. for example if it is desired to move the template 6 in one direction only then only one of the windings of the clutches will be energised to couple the associated output pinion to the main transmission. Thus, the template 6 will be moved in the selected direction by rotation of the pinion, which motion is transferred to the associated rack 51, 52, and hence through the linkage to the appropriate carriage. Since the second output pinion of the pair is meshed with the rack it will be rotated by the rack and thus if it is required to reverse the direction of movement of the template 6, when the first clutch is de-energised and the second clutch is energised to reverse the direction, there will be no backlash to be taken up before the direction of movement of the template is changed. If during this second step it is desired to move the template 6 in both paths then the windings of two clutches are energised; one from each of the pairs of clutches. Thus if the template is required to move at, for example, an angle of 45 relative to the paths then the windings of two clutches will be energised. It will be appreciated that when moving in this direction and particularly when moving round a curve of varying radius, then the amount of movement required in a given direction may vary non-linearly with time. To enable this to take place the coupling forces of the clutches are arranged to be sufficiently small that when a resisting force is applied by virtue of the template being restrained from movement in said direction then the clutches will slip until said retarding force is removed. The actual path of movement of the template 6 is determined by the slot which is always engaged with the guide device 73 located concentrically with the needle. Thus mirror variations in direction, such as following a shallow curve are controlled bythe slot, the template drive transmission merely pulling or pushing the template is a straight line along the path required.

Just before the end of a machining cycle, the last pulse from the sequential unit is arranged to fire the thyristor D2 of Module D to energise the winding ofthe lift solenoid 88 on the control carriage 56. There is a slight time lag in the response of the solenoid 88 and therefore the winding of the solenoid 88 is energised a sufficient time before the end of the cycle to enable the .cycle to be completed before the solenoid responds to lift the carriage 56 from the template 6.

When the control carriage 56 is lifted up the spring latch automatically located in a slot provided in the control carriage 56 to maintain the carriage in the raised position. Simultaneously the contacts of the mithe on position to bring the machine to a standstill. As

described previously the light sensitive device is arranged to ensure that the machine is stopped with the needle in the raised position and thus the brake is actuated to the on position only when light sensitive device 2 5 is irradiated.

If the light sensitive device is not irradiated, there is release of the brake and a reduced current is switched back to the windings of the clutch again under the control of Module E and a slipping clutch effect is achieved.

Module E comprises a transistor pair operating as a bistable switch arranged to operate only when the contacts of microswitch M/SS are closed i.e. when the carriage is lifted. The bistable switch is controlled in response to output sifnals from the photo-sensitive device 25. When the device 25 is irradiated, the drive switches from slipping clutch to the brake and vice versa. The brake is then actuated and halts the machine operation with the needle raised. Four potentiometers P1, P2, P3, P4 are included in circuit between the outputs of the direction control unit 85a and the windings of the clutches 47, 48; 49, 50; to obtain a consistent stitch in all directions; the potentiometers reducing the power available to the clutches to vary the stitch length. An overall change of stitch length is effected by replacing pinion 33 (FIG. 2) with another pinion having a predetermined number of teeth. A spring-loaded ball (not shown) is provided for retaining pinion 33 on shaft 34 outside the gear box to allow quick and easy overall variation of stitch length.

The machine may include a cutter to automatically cut the thread passing through the needle 3 (FIG. 5) when the template is withdrawn. The cutter apparatus comprises a scissors arrangement (FIG. 6) including pivoted blades 100, 101 mounted on the needle plate 102 and operated by a solenoid 103 (FIG. 7) through a Bowden type cable 104 (FIG. 6).

The scissors arrangement includes lever 100, pivotally mounted intermediate its length on the underside of the throat plate 102. The lever 100 has longitudinally extending slots 105, 106 on either side of the pivotal mounting 107, one of which slots 105, is engaged by an upstanding pin 108 located on the second lever 101. The second lever 101 is pivotally mounted at 109 adjacent one end, on the underside of the throat plate 102 and has the cable 104 connected thereto on the side of the pivotal mounting remote from the upstanding pin 108. The cable 104 is connected to the armature of the solenoid 103 such that energisation of the solenoid winding causes the cable to urge the lever 101 about the pivot 109. The winding of the solenoid 103 is energised via relay 110 from the signal which controls the de-energisation of the clutch and the actuation of the main brake 5 at the termination of a machining cycle.

Module M (FIG. 7) controls the energisation of the winding of relay 110 (Module M). The line from the microswitch M/SS is positive and the voltage thereon is applied via a diode which bypasses thyristor D3 of Module N to charge a capacitor. A transistor circuit with a resistor/capacitor time delay effects the firing of thyristor D3 which discharges the capacitor through the relay coil 110 and back to the microswitch M/S5 line which goes negative when the brake is applied. Two conditions must be fulfilled to enable the relay winding to be energised:

a. the machine must be stopped with the needle in the raised position which means that the brake will have been applied. Thus the microswitch M/SS line will be at negative potential to accept the capacitor discharge referred to above b. a signal from the sequential unit 84 is directed via the matrix of programme unit 85 to the base of the thyristor D3 triggering transistor, at the end of the sewing. cycle. The resistor/capacitor delay on the trigger transistor is to ensure that the needle has definitely stopped on the raised position and is not ready to recycle via the slipping clutch. The thyristor provides sufficient delay for the cutting operation to be effected together with the delay provided by the time constant olthe capacitative discharge circuit. The thyristor D3 is fired only when the needle is in the raised position. The capacitor discharges to supply energising current to the winding of the relay 119 to effect energisation of the winding of solenoid 103. This causes the second lever 101 to pivot and the upstanding pin 108 moves through 'an arcuate path to pivot the first lever in the opposite direction from that of lever 101, thus providing a scissors movement. The scissors action is arranged to take place across the path of the thread to enable the template 6 to be withdrawn from the machine. A coil spring is wound concentrically about the pivot pin 109 and is arranged to bias the scissors levers 100, 101, to the open position. Lever 101 is set to measure the required length of thread necessary at the shuttle to enable the needle to pick up the thread on the next cycle. Lever 100 which has a delayed action caused by the action of the upstanding pin 108 in the slot 105, cuts the thread close to the needle plate 102 at the end of its travel.

It will be appreciated that the invention has been described by way of example only and is capable of considerable modification. For instance, the counter of the sequential unit 84 may be extended by providing a pair of relays each having four change over poles and arranged to be switched at the end of a counting sequence to add eight further counting stages if required. The sequential unit would have a count of 18 and the operation of the relays would be controlled inresponse to the firing of a thyristor in Module N.

I claim:

1. Profile stitching apparatus including a power driven sewing machine having drive means and a needle, a stitching tracker plate having a slotted profile arranged to be moved with the slot. in register with the needle of the machine to sew along the profile, guide means, arranged along one longitudinal edge of the tracker plate, further guide means arranged along a lateral edge of the tracker plate, a first carriage member, a first rack operatively connected to the first carriage member and arranged to engage the guide means, a second carriage member, a second rack operatively connected to the second carriage member and arranged to engage the further guide means, transmission means arranged to couple the plate to the drive means for the machine to allow the plate to move relatively to the needle of the machine, said transmission means including a gear assembly having a pair of first pair of contra-rotatable pinions co-operable with the first rack to permit the tracker plate to be moved in a direction transversely of the one longitudinal edge, and the gear assembly including a second pair of contra-rotating pinions co-operable with the second rack to permit the tracker plate to be moved in a direction different from the first mentioned direction, and means included in the transmission means for moving the tracker plate in timed relationship with the operation of the machine such that the tracker plate is moved only when the needle is clear of the workpiece.

2. Apparatus as claimed inclaim 1 wherein the transmission means further includes control means, and wherein said first and second guide means are arranged to co-operate with the control means to control the relative movement between the tracker plate and the needle of the machine.

3. Apparatus as claimed in claim 1 wherein the transmission means further includes an electromagnetic clutch operatively associated with each pinion, and wherein energisation of the winding of a respective electromagnetic clutch effects rotation of the respective pinion tomove the rack associated therewith.

4. Apparatus as claimed in claim 1 wherein the transmission means further' includes intermittent drive means arranged to impart intermittent movement to the tracker plate to move the tracker plate in timed relationship with the operation of the machine, and to permit the tracker plate to be moved only when the needle is clear of the workpiece, said intermittent drive means including'a Geneva gear mechanism coupled between the transmission means and the gear assembly to synchronise the operation of the machine with the movement of the tracker plate.

5. Apparatus as claimed in claim 1 wherein each carriage member includes at least one pair of guide wheels mounted with their axes of rotation vertical and arranged to engage one on each side of the respective guide means of the tracker plate to allow the carriage members to traverse the length of the respective guide means.

6. Apparatus as claimed in claim 1 wherein each a guide means on the tracker plate is provided with a plurality of notches and each carriage member is provided with a respective switch member the contacts of which are arranged to be closed whenever the switch member of a carriage member is aligned with a notch on the respective edge of the tracker plate.

7. Apparatus as claimed in claim 6, wherein the first carriage member includes a main body portion pivotable between a raised and lowered position said carriage member being provided with a further switch memberwhose contacts are actuated when the main portion of the first carriage member is raised or lowered,

8. Apparatus as claimed in claim 6, further including a sequencing unit, and wherein said switch members comprise first and second microswitches provided on the first and second carriage members respectively, the first and second microswitches being connected electrically in series and to the sequencing unit, which includes counting means arranged to be stepped sequentially in response to pulses generated each time the contacts of the first and second microswitches are actu-' ated upon alignment of the switches with the notches in the guide means of the tracker plate.

9. Apparatus as claimed in claim 8 further including a solenoid operatively associated with the first carriage member, an arm connected to the armature of said solenoid for retaining the first carriage member in a raised position, and a trigger delay circuit operatively connected to the solenoid and the sequencing unit, wherein the contacts of the further switch member are actuated whenever the tracker plate is in the correct position for commencement of a machine cycle to thereby complete a circuit to said sequencing unit to reset the counting means to the beginning ofa counting cycle, said trigger delay circuit being responsive to the resetting of the sequencing unit to supply energising current to the winding of said solenoid, and wherein energisation of the winding of the solenoid effects actuation of the armature to acutate the arm and allow the carriage member to move into engagement with the tracker plate.

10. Apparatus as claimed in claim 9 wherein the winding ofthe solenoid is de-energised upon movement of the first carriage member and power is supplied to the electromagnetic clutches of the gear assembly.

11. Apparatus as claimed in claim 8 further including a programme selector unit and a direction control unit connected to the programme unit, wherein the stepping of the counting means supplies an output pulse via a matrix of the programme selector unit to the direction control unit providing a preselected current path to at least one of the electromagnetic clutches of the gear assembly to effect energisation of the winding thereof and to cause the respective pinion to be rotated to move the associated rack.

12. Apparatus as claimed in claim 9 further including a solenoid operatively associated with the first carriage member, an arm connected to the armature of said further solenoid, and another switch member actuated in response to raising of the first carriage member, wherein the stepping of the counting means to a predetermined step indicative of the last step in the machine cycle produces an output pulse for the triggering of the trigger delay circuit to thereby provide a current pulse therefrom for energisation of the winding of the further solenoid to allow the arm thereof to be actuated to raise the first carriage member and the contacts of said another switch member to remove power from the windings of the electromagnetic clutches.

13. Apparatus as claimed in claim 4 further including a disc coupled to the transmission means and having at least two apertures therein, a light source, a light responsive device, said light source being arranged to direct light through said apertures to the light response device to produce output signals therefrom when irradiated by the light source, a brake/clutch unit of the transmission means, and switching means connected in circuit between the output of said light responsive device and the brake/clutch unit of the transmission means and responsive to output signals from said light responsive device to prevent the brake being applied when the light sensitive device is not irradiated.

14. Apparatus as claimed in claim 13 wherein in the absence of output signals from said light sensitive device, the switching means allows release of the brake and interrupts current flow to the clutch of the transsembly via the universal coupling, said input shaft having an interchangeable pinion removably located thereon and having a number of teeth in accordancewith the particular stitch length required.

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1. Profile stitching apparatus including a power driven sewing machine having drive means and a needle, a stitching tracker plate having a slotted profile arranged to be moved with the slot in register with the needle of the machine to sew along the profile, guide means, arranged along one longitudinal edge of the tracker plate, further guide means arranged along a lateral edge of the tracker plate, a first carriage member, a first rack operatively connected to the first carriage member and arranged to engage the guide means, a second carriage member, a second rack operatively connected to the second carriage member and arranged to engage the further guide means, transmission means arranged to couple the plate to the drive means for the machine to allow the plate to move relatively to the needle of the machine, said transmission means including a gear assembly having a pair of first pair of contra-rotatable pinions co-operable with the first rack to permit the tracker plate to be moved in a direction transversely of the one longitudinal edge, and the gear assembly including a second pair of contra-rotating pinions cooperable with the second rack to permit the tracker plate to be moved in a direction different from the first mentioned direction, and means included in the transmission means for moving the tracker plate in timed relationship with the operation of the machine such that the tracker plate is movEd only when the needle is clear of the workpiece.
 2. Apparatus as claimed in claim 1 wherein the transmission means further includes control means, and wherein said first and second guide means are arranged to co-operate with the control means to control the relative movement between the tracker plate and the needle of the machine.
 3. Apparatus as claimed in claim 1 wherein the transmission means further includes an electromagnetic clutch operatively associated with each pinion, and wherein energisation of the winding of a respective electromagnetic clutch effects rotation of the respective pinion to move the rack associated therewith.
 4. Apparatus as claimed in claim 1 wherein the transmission means further includes intermittent drive means arranged to impart intermittent movement to the tracker plate to move the tracker plate in timed relationship with the operation of the machine, and to permit the tracker plate to be moved only when the needle is clear of the workpiece, said intermittent drive means including a Geneva gear mechanism coupled between the transmission means and the gear assembly to synchronise the operation of the machine with the movement of the tracker plate.
 5. Apparatus as claimed in claim 1 wherein each carriage member includes at least one pair of guide wheels mounted with their axes of rotation vertical and arranged to engage one on each side of the respective guide means of the tracker plate to allow the carriage members to traverse the length of the respective guide means.
 6. Apparatus as claimed in claim 1 wherein each guide means on the tracker plate is provided with a plurality of notches and each carriage member is provided with a respective switch member the contacts of which are arranged to be closed whenever the switch member of a carriage member is aligned with a notch on the respective edge of the tracker plate.
 7. Apparatus as claimed in claim 6, wherein the first carriage member includes a main body portion pivotable between a raised and lowered position said carriage member being provided with a further switch member whose contacts are actuated when the main portion of the first carriage member is raised or lowered.
 8. Apparatus as claimed in claim 6, further including a sequencing unit, and wherein said switch members comprise first and second microswitches provided on the first and second carriage members respectively, the first and second microswitches being connected electrically in series and to the sequencing unit, which includes counting means arranged to be stepped sequentially in response to pulses generated each time the contacts of the first and second microswitches are actuated upon alignment of the switches with the notches in the guide means of the tracker plate.
 9. Apparatus as claimed in claim 8 further including a solenoid operatively associated with the first carriage member, an arm connected to the armature of said solenoid for retaining the first carriage member in a raised position, and a trigger delay circuit operatively connected to the solenoid and the sequencing unit, wherein the contacts of the further switch member are actuated whenever the tracker plate is in the correct position for commencement of a machine cycle to thereby complete a circuit to said sequencing unit to reset the counting means to the beginning of a counting cycle, said trigger delay circuit being responsive to the resetting of the sequencing unit to supply energising current to the winding of said solenoid, and wherein energisation of the winding of the solenoid effects actuation of the armature to acutate the arm and allow the carriage member to move into engagement with the tracker plate.
 10. Apparatus as claimed in claim 9 wherein the winding of the solenoid is de-energised upon movement of the first carriage member and power is supplied to the electromagnetic clutches of the gear assembly.
 11. Apparatus as claimed in claim 8 further including a programme selector unit aNd a direction control unit connected to the programme unit, wherein the stepping of the counting means supplies an output pulse via a matrix of the programme selector unit to the direction control unit providing a preselected current path to at least one of the electromagnetic clutches of the gear assembly to effect energisation of the winding thereof and to cause the respective pinion to be rotated to move the associated rack.
 12. Apparatus as claimed in claim 9 further including a solenoid operatively associated with the first carriage member, an arm connected to the armature of said further solenoid, and another switch member actuated in response to raising of the first carriage member, wherein the stepping of the counting means to a pre-determined step indicative of the last step in the machine cycle produces an output pulse for the triggering of the trigger delay circuit to thereby provide a current pulse therefrom for energisation of the winding of the further solenoid to allow the arm thereof to be actuated to raise the first carriage member and the contacts of said another switch member to remove power from the windings of the electromagnetic clutches.
 13. Apparatus as claimed in claim 4 further including a disc coupled to the transmission means and having at least two apertures therein, a light source, a light responsive device, said light source being arranged to direct light through said apertures to the light response device to produce output signals therefrom when irradiated by the light source, a brake/clutch unit of the transmission means, and switching means connected in circuit between the output of said light responsive device and the brake/clutch unit of the transmission means and responsive to output signals from said light responsive device to prevent the brake being applied when the light sensitive device is not irradiated.
 14. Apparatus as claimed in claim 13 wherein in the absence of output signals from said light sensitive device, the switching means allows release of the brake and interrupts current flow to the clutch of the transmission means to effect slipping thereof.
 15. Apparatus as claimed in claim 11 further including plurality of potentiometers connected between the outputs of the direction control unit and the respective windings of the electomagnetic clutches to reduce the power available to the windings and effectively vary the stitch length of the machine.
 16. Apparatus as claimed in claim 14 further including a thread cutting device provided on the machine beneath the needle plate thereof, said device including a solenoid whose winding is energised in response to application of the brake to cut the thread and allow the tracker plate to be removed from the machine.
 17. Apparatus as claimed in claim 4 further including a universal coupling, wherein the intermittentt drive means is connected to the input shaftt of the gear assembly via the universal coupling, said input shaft having an interchangeable pinion removably located thereon and having a number of teeth in accordance with the particular stitch length required. 